Packed Level Actors or Level Instances with baked lightmaps

Were baked lights discarded immediately after baking, in the editor, or during runtime?

I am using PLA blueprints and all works well when baking with CPU. But GPU bakes end up in no lights baked in = black geometry.
When I drag in the same thing as Level, not BP, all bakes correctly on both. Kind of to be expected, as that is then a Level Instance. No clue how to make BP thing work too. Sort of makes the whole thing unusable.

Did you manage to find a solution?